Solvent-free protocol for amide bond formation via trapping of nascent phosphazenes with carboxylic acids

One-Pot Solvent-Free Synthesis of N,N-Bis(2-Hydroxyethyl) Alkylamide from Triglycerides Using Zinc-Doped Calcium Oxide Nanospheroids as a Heterogeneous Catalyst

N,N-Bis(2-hydroxyethyl) alkylamide or fatty acid diethanolamides (FADs) were prepared from a variety of triglycerides using diethanolamine in the presence of different transition metal-doped CaO nanocrystalline heterogeneous catalysts. The Zn-doped Cao nanospheroids were found to be the most efficient heterogeneous catalyst, with complete conversion of natural triglycerides to fatty acid diethanolamide in 30 min at 90 °C. The Zn/CaO nanoparticles were recyclable for up to six reaction cycles and showed complete conversion even at room temperature. The amidation reaction of natural triglycerides was found to follow the pseudo-first-order kinetic model, and the first-order rate constant was calculated as 0.171 min–1 for jatropha oil aminolysis. The activation energy (Ea) and pre-exponential factor (A) for the same reaction were found to be 47.8 kJ mol–1 and 4.75 X 108 min-1, respectively.

Nonclassical Routes for Amide Bond Formation

The present review offers an overview of nonclassical (e.g., with no pre- or in situ activation of a carboxylic acid partner) approaches for the construction of amide bonds. The review aims to comprehensively discuss relevant work, which was mainly done in the field in the last 20 years. Organization of the data follows a subdivision according to substrate classes: catalytic direct formation of amides from carboxylic and amines ( section 2 ); the use of carboxylic acid surrogates ( section 3 ); and the use of amine surrogates ( section 4 ). The ligation strategies (NCL, Staudinger, KAHA, KATs, etc.) that could involve both carboxylic acid and amine surrogates are treated separately in section 5 .

A facile, rapid, one-pot regio/stereoselective synthesis of 2-iminothiazolidin-4-ones under solvent/scavenger-free conditions

A rapid and efficient one pot solvent/scavenger-free protocol for the synthesis of 2-iminothiazolidin-4-ones has been developed. Interestingly, the regio/stereoselective synthesis affords the regioisomeric (Z)-3-alkyl/aryl-2-(2-phenylcyclohex-2-enylimino)thiazolidin-4-one as the sole product in good yield. The selectivities observed have been rationalized based on the relative magnitude of the allylic strains developed during the course of the reaction. This is the first report wherein the impact of allylic strains in directing the regiocyclization has been noted.